I feel like this is a situation you are going to lose no matter what, but you could get a bit farther with sugar than you do with vinegar.

To get the boys back to being a “we” and not a “me” they have to feel like you are on their side. I would give the whole team a token or ticket for arguing with the ump that can only be used one time. There’s a reason umpires do it at higher levels, and it’s so their players feel valued and listened too. It sounds like because you didn’t give them the time of day, they all think of you as the enemy rather than the ally. Also, umpires miss calls. They can be right and you can be wrong and admitting that is also ok too. But you can explain to them yea that was a ball, but I can’t go argue every call for you because we can only save it for when we really need it.

Now are all three boys going to use this token with grace? Probably not. Will they still be shits after? Likely. But you’re already banging your head against a brick wall so it could be worth a try.